Question

What is (vector a - vector b) x (vector a + vector b) equal to?

a. vector 0

b. vector a x vector b

c. 2(vector a x vector b)

d. |vector a|² - |vector b|²

Answer 1

Correct option c. 2(vector a x vector b)

Explanation:

(vector a - vector b) x (vector a + vector b)

= vector a x vector a + vector a x vector b - vector b x vector a + vector b - vector b

= 0 + vector a x vector b + vector a x vector b + 0

= 2(vector a x vector b)